High intensity white light sources are interesting for various applications including spots, stage-lighting, headlamps and digital light projection. One way to provide a high intensity white light source is to make use of so-called light concentrators where shorter wavelength light is converted to longer wavelengths in a highly transparent luminescent material. A rod of such a transparent luminescent material is illuminated by e.g. LEDs to produce longer wavelengths within the rod. Converted light staying in the luminescent material, such as a doped garnet, can then be extracted from one of the surfaces of the rod leading to an intensity gain. However, such a luminescent convertor based light source may be inefficient and obtaining extremely high intensities is not easy. Another method of obtaining high intensity light is to use a high intensity laser beam which is focused on a rotating phosphor wheel. However, the mechanical moving part reduces the reliability of the system. Further, to provide high intensity white light an additional component of blue light may be required.
US patent application 2013/308332 discloses a device for generating white light that includes at least one light source and at least one conversion medium. The light source emits light in the blue and/or ultraviolet spectral range. The light from the light source is generated by a laser and the light from the light source is focused by an optical system onto the conversion medium. The conversion medium converts at least part of the incident light into a different spectral range. In FIG. 7 of US2013/308332, converted light is deflected by a dichroic mirror, so that it may be fed into a light guide. The dichroic mirror is configured to reflect the converted radiation, but to transmit light from said light source. For producing white light, another laser or a blue light source is employed, and the light therefrom is separately fed into the light guide to obtain a blue component in the white light.